-=::) Dante (::=-
Strictly speaking you could probably finish putting out the tiles before doing the supply round
The rules explicitly state that the remaining tiles are drawn after the Supply Round occurs.
Peloponnes English Rules wrote:
If one of the tiles is a Supply Round (in the “B” and “C” stacks), the game is briefly interrupted:
A Supply Round occurs (see Point 7),
more Tiles are drawn and placed face-up until there are again a total of 5. Then the game continues.